U.S. patent application number 11/029471 was filed with the patent office on 2006-07-06 for thermoelectric heat exchange element.
This patent application is currently assigned to Caterpillar Inc. Invention is credited to James J. Callas, Mahmoud A. Taher.
Application Number | 20060144052 11/029471 |
Document ID | / |
Family ID | 36218560 |
Filed Date | 2006-07-06 |
United States Patent
Application |
20060144052 |
Kind Code |
A1 |
Callas; James J. ; et
al. |
July 6, 2006 |
Thermoelectric heat exchange element
Abstract
A thermoelectric heat exchange module includes a first substrate
including a heat receptive side and a heat donative side and a
series of undulatory pleats. The module may also include a
thermoelectric material layer having a ZT value of 1.0 or more
disposed on at least one of the heat receptive side and the heat
donative side, and an electrical contact may be in electrical
communication with the thermoelectric material layer.
Inventors: |
Callas; James J.; (Peoria,
IL) ; Taher; Mahmoud A.; (Peoria, IL) |
Correspondence
Address: |
CATERPILLAR/FINNEGAN, HENDERSON, L.L.P.
901 New York Avenue
WASHINGTON
DC
20001-4413
US
|
Assignee: |
Caterpillar Inc
|
Family ID: |
36218560 |
Appl. No.: |
11/029471 |
Filed: |
January 6, 2005 |
Current U.S.
Class: |
62/3.7 |
Current CPC
Class: |
F25B 21/02 20130101;
F28F 3/046 20130101; H01L 35/30 20130101 |
Class at
Publication: |
062/003.7 |
International
Class: |
F25B 21/02 20060101
F25B021/02 |
Claims
1. A thermoelectric heat exchange module, comprising: a first
substrate including a heat receptive side and a heat donative side
and a series of undulatory pleats; a thermoelectric material layer
having a ZT value of 1.0 or more disposed on at least one of the
heat receptive side and the heat donative side; and an electrical
contact in electrical communication with the thermoelectric
material layer.
2. The thermoelectric heat exchange module according to claim 1,
further including: a second substrate including a heat receptive
side and a heat donative side and a series of undulatory pleats;
wherein the second substrate is arranged with respect to the first
substrate such that a plurality of fluid flow passages is formed
between the first and second substrates by opposing undulatory
pleats of the first and second substrates.
3. The thermoelectric heat exchange module according to claim 2,
further including a thermoelectric material layer having a ZT value
of 1.0 or more disposed on at least one of the heat receptive side
and the heat donative side of the second substrate.
4. The thermoelectric heat exchange module according to claim 1,
wherein the thermoelectric material layer includes a plurality of
thin film layers.
5. The thermoelectric heat exchange module according to claim 1,
wherein the ZT value of the thermoelectric material layer is
between 1.0 and 10.
6. The thermoelectric heat exchange module according to claim 1,
wherein the thermoelectric material layer includes a
zero-dimensional quantum dots thermoelectric material.
7. The thermoelectric heat exchange module according to claim 1,
wherein the thermoelectric material layer includes a
one-dimensional nano wires thermoelectric material.
8. The thermoelectric heat exchange module according to claim 1,
wherein the thermoelectric material layer includes a
two-dimensional quantum well thermoelectric material.
9. The thermoelectric heat exchange module according to claim 2,
wherein the plurality of fluid flow passages provides the
thermoelectric heat exchange module with a heat transfer surface
area density value of at least 500 Ft.sup.2/Ft.sup.3.
10. The thermoelectric heat exchange module according to claim 2,
wherein the plurality of fluid flow passages provides the
thermoelectric heat exchange module with a heat transfer surface
area density value of between 800 Ft.sup.2/Ft.sup.3 and 1,000
Ft.sup.2/Ft.sup.3.
11. The thermoelectric heat exchange module according to claim 1,
wherein the first substrate includes a metal.
12. The thermoelectric heat exchange module according to claim 1,
wherein the substrate includes a ceramic.
13. A work machine, comprising: an engine that produces an exhaust
stream; an exhaust system configured to carry the exhaust stream;
and a thermoelectric heat exchange module disposed in the exhaust
system, the thermoelectric heat exchange module including: a first
substrate including a heat receptive side and a heat donative side
and a series of undulatory pleats; a thermoelectric material layer
having a ZT value of 1.0 or more disposed on at least one of the
heat receptive side and the heat donative side; and an electrical
contact in electrical communication with the thermoelectric
material layer.
14. The work machine of claim 13, wherein the thermoelectric heat
exchange module further includes: a second substrate including a
heat receptive side and a heat donative side and a series of
undulatory pleats; and a thermoelectric material layer having a ZT
value of 1.0 or more disposed on at least one of the heat receptive
side and the heat donative side of the second substrate; wherein
the second substrate is arranged with respect to the first
substrate such that a plurality of fluid flow passages is formed
between the first and second substrates by opposing undulatory
pleats of the first and second substrates.
15. The work machine of claim 14, wherein the plurality of fluid
flow passages provides the thermoelectric heat exchange module with
a heat transfer surface area density value of between 800
Ft.sup.2/Ft.sup.3 and 1,000 Ft.sup.2/Ft.sup.3.
16. The work machine of claim 13, wherein the ZT value of the
thermoelectric material layer is between 1.0 and 10.
17. The work machine of claim 13, wherein the thermoelectric
material layer includes at least one material selected from a group
including a zero-dimensional quantum dots thermoelectric material,
a one-dimensional nano wires thermoelectric material, and a
two-dimensional quantum well thermoelectric material.
18. An method of recovering energy from a work machine exhaust
system, comprising: flowing an exhaust stream from an engine
through a thermoelectric heat exchange module that includes: a
first substrate including a heat receptive side and a heat donative
side and a series of undulatory pleats; a thermoelectric material
layer having a ZT value of 1.0 or more disposed on at least one of
the heat receptive side and the heat donative side; and an
electrical contact in electrical communication with the
thermoelectric material layer; using the flowing exhaust stream to
heat a first side of the thermoelectric material; cooling a second
side of the thermoelectric material to generate a temperature
gradient across the thermoelectric material and a related voltage
level; providing the voltage level on the electrical contact for
use by at least one electrically powered component.
19. The method according to claim 18, further including: converting
the voltage to a desired voltage level by using a DC-DC
converter.
20. The method according to claim 18, wherein the thermoelectric
heat exchange module further includes: a second substrate including
a heat receptive side and a heat donative side and a series of
undulatory pleats; and a thermoelectric material layer having a ZT
value of 1.0 or more disposed on at least one of the heat receptive
side and the heat donative side of the second substrate; wherein
the second substrate is arranged with respect to the first
substrate such that a plurality of fluid flow passages is formed
between the first and second substrates by opposing undulatory
pleats of the first and second substrates.
21. The method according to claim 20, wherein the plurality of
fluid flow passages provides the thermoelectric heat exchange
module with a heat transfer surface area density value of between
800 Ft.sup.2/Ft.sup.3 and 1,000 Ft.sup.2/Ft.sup.3.
22. The method of claim 18, wherein the ZT value of the
thermoelectric material layer is between 1.0 and 10.
Description
TECHNICAL FIELD
[0001] This disclosure relates generally to thermoelectric heat
exchange systems, and more particularly to a thermoelectric heat
exchange element.
BACKGROUND
[0002] A thermoelectric material is a type of material that can
directly convert thermal energy into electrical energy or vice
versa. Thermoelectric materials can produce a voltage potential in
the presence of a temperature gradient across the thermoelectric
materials and, alternately, can produce a temperature gradient in
response to an applied voltage potential. The magnitudes of the
temperature gradient and the voltage may be proportionally
related.
[0003] Based on these properties, attempts have been made to create
thermoelectric-enhanced heat exchangers to include thermoelectric
materials in heat exchanger arrangements. For example, U.S. Pat.
No. 6,557,354 ("the '354 patent") issued to Chu et al. on May 6,
2003, describes a thermoelectric-enhanced heat exchanger for
facilitating heat removal within a cooling system for an electronic
device. However, the heat exchanger described in the '354 patent,
like other conventional thermoelectric-enhanced heat exchangers,
may suffer from low efficiencies due to the use of bulk
thermoelectric materials. Further, the efficiency of the heat
exchanger of the '354 patent may be limited by a low surface area
to volume configuration of the heat exchange elements.
[0004] Methods and systems consistent with certain features of the
disclosed specification are directed to solving one or more of the
problems set forth above.
SUMMARY OF THE INVENTION
[0005] One aspect of the present disclosure includes a
thermoelectric heat exchange module having a first substrate
including a heat receptive side and a heat donative side and a
series of undulatory pleats. The module may also include a
thermoelectric material layer having a ZT value of 1.0 or more
disposed on at least one of the heat receptive side and the heat
donative side, and an electrical contact may be in electrical
communication with the thermoelectric material layer.
[0006] Another aspect of the present disclosure includes a work
machine.
[0007] The work machine may include an engine that produces an
exhaust stream. An exhaust system may be configured to carry the
exhaust stream, and a thermoelectric heat exchange module may be
placed in the exhaust system. The thermoelectric heat exchange
module may include a first substrate including a heat receptive
side and a heat donative side and a series of undulatory pleats. A
thermoelectric material layer having a ZT value of 1.0 or more may
be disposed on at least one of the heat receptive side and the heat
donative side, and an electrical contact may be in electrical
communication with the thermoelectric material layer.
[0008] Another aspect of the present disclosure includes a method
for recovering energy from a work machine exhaust system. The
method may include flowing an exhaust stream from an engine through
a thermoelectric heat exchange module that includes a first
substrate including a heat receptive side and a heat donative side
and a series of undulatory pleats, a thermoelectric material layer
having a ZT value of 1.0 or more disposed on at least one of the
heat receptive side and the heat donative side, and an electrical
contact in electrical communication with the thermoelectric
material layer. The method may further include using the flowing
exhaust stream to heat a first side of the thermoelectric material
and cooling a second side of the thermoelectric material to
generate a temperature gradient across the thermoelectric material
and a related voltage level. The voltage level may be provided on
the electrical contact for use by at least one electrically powered
component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate several
embodiments and together with the description, serve to explain the
principles of the disclosed embodiments. In the drawings:
[0010] FIG. 1 is a pictorial illustration of a work machine
incorporating an exemplary high efficiency thermoelectric heat
exchange system;
[0011] FIG. 2 provides a block diagram of an exemplary high
efficiency thermoelectric heat exchange system consistent with
certain disclosed embodiments;
[0012] FIGS. 3A-3F illustrate exemplary configurations of
thermoelectric materials consistent with certain disclosed
embodiments;
[0013] FIG. 4 is a pictorial illustration of an exemplary
thermoelectric module consistent with certain disclosed
embodiments; and
[0014] FIG. 5 illustrates a cross-sectional view taken along the
line 5-5 in FIG. 4.
DETAILED DESCRIPTION
[0015] Reference will now be made in detail to exemplary
embodiments, which are illustrated in the accompanying drawings.
Wherever possible, the same reference numbers will be used
throughout the drawings to refer to the same or like parts.
[0016] FIG. 1 illustrates an exemplary high efficiency
thermoelectric heat exchange system 110 incorporated into a work
machine 100. Work machine 100 may refer to any type of fixed or
mobile machine that performs some type of operation associated with
a particular industry, such as mining, construction, farming,
transportation, etc. and operates between or within work
environments (e.g., construction site, mine site, power plants,
on-highway applications, etc.). Work machine 100 may also refer to
any type of automobile or commercial vehicle. Non-limiting examples
of mobile machines include on-highway vehicles, commercial
machines, such as trucks, cranes, earth moving vehicles, mining
vehicles, backhoes, material handling equipment, farming equipment,
marine vessels, aircraft, and any type of movable machine that
operates in a work environment, and/or cars, vans, trucks, and any
type of automobiles and commercial vehicles. Although, as shown in
FIG. 1, work machine 100 is an on-highway truck, it is contemplated
that work machine 100 may be any type of work machine. Further,
work machine 100 may be a conventionally powered, hybrid electric
powered, and/or fuel cell powered work machine.
[0017] As shown in FIG. 1, work machine 100 may include an engine
102 to provide power to work machine 100 and a variety of
components (not shown) on work machine 100. Engine 102 may be any
type of engine, such as an internal combustion engine. Engine 102
may generate significant levels of waste heat when providing power
to work machine 100. This waste heat may be expelled to the
atmosphere through an exhaust system. In certain disclosed
embodiments, work machine 100 may incorporate a thermoelectric heat
exchange system 110 to recover at least a portion of the thermal
energy associated with the waste heat expelled by the exhaust
system.
[0018] Thermoelectric heat exchange system 110 may be configured to
convert waste heat generated by engine 102 to electrical energy.
Thermoelectric heat exchange system 110 may also be configured to
perform different applications under certain situations. For
example, thermoelectric heat exchange system 110 may be configured
to convert energy from any source of heat on work machine 100, or
any other type of device or application, into electrical energy.
Further, thermoelectric heat exchange system 110 may be configured
to provide heating and/or cooling in a variety of applications
(e.g., heating and/or cooling air or other components of work
machine 100). Such heating and/or cooling may be accomplished by
heating and/or cooling a heat transfer fluid using an applied
voltage supplied to thermoelectric materials of thermoelectric heat
exchange system 110. The functional structures of thermoelectric
heat exchange system 110 are illustrated in FIG. 2.
[0019] As shown in FIG. 2, thermoelectric heat exchange system 110
may include a thermoelectric module 202, a DC-DC converter 204, a
controller 206, a heat donative fluid flow 208, a heat receptive
fluid flow 210, and an electric bus 212. Through use of
thermoelectric materials, thermoelectric module 202 may recover at
least a portion of the energy associated with the waste heat
produced by engine 102. Thermoelectric materials may be operated
based on the Seebeck effect or the Peltier effect. FIG. 3A
illustrates an exemplary configuration of thermoelectric materials
operating based on the Peltier effect.
[0020] As shown in FIG. 3A, thermoelectric materials may be
semiconductors that are packaged in a thermoelectric couple 302.
Thermoelectric couple 302 may include a positive-type P element 304
and a negative-type N element 306. Thermoelectric couple 302 may
also include junctions 308-1 to 308-3. When electrical power 310
from a current source 312 is passed through thermoelectric couple
302, a temperature gradient AT across junctions 308-1 and 308-2 and
junctions 308-3 of thermoelectric couple 302 may be generated. Such
phenomenon is known as the Peltier effect. The polarity of the
temperature gradient (i.e., which junction or junctions have a high
temperature) may be determined by the polarity of current source
312 providing power 310 to thermoelectric couple 302.
[0021] Conversely, as shown in FIG. 3B, electrical power 310 may be
generated through an electrical load 314 if a temperature
difference AT is maintained between the junctions 308-1 and 308-2
and junction 308-3 of thermoelectric couple 302 (a phenomenon known
as the Seebeck effect). This temperature difference can be
maintained by providing a heat source at one junction and a heat
sink at the other junctions.
[0022] The effectiveness of a thermoelectric material in converting
electrical energy to heating or cooling energy (i.e., coefficient
of performance "COP"), or converting heat energy to electrical
energy (conversion efficiency ".eta.") depends on the
thermoelectric material's figure of merit termed "Z" and the
average operating temperature "T". Z is a material characteristic
that is defined as: Z = S 2 .times. .sigma. .lamda. , ##EQU1##
where S is the Seebeck coefficient of the material, .sigma. is the
electrical conductivity of the material, and .lamda. is the thermal
conductivity of the material.
[0023] Because Z changes as a function of temperature, Z may be
reported along with the temperature T, at which the properties are
measured. Thus, the dimensionless product ZT may be used instead of
Z to reflect the effectiveness of the thermoelectric material. To
improve the COP or .eta. of thermoelectric materials, an increase
in ZT may be necessary.
[0024] From the definition of Z, an independent increase in the
Seebeck coefficient and/or electrical conductivity, or an
independent decrease in the thermal conductivity may contribute to
a higher ZT. Conventional low ZT thermoelectric materials, also
known as bulk thermoelectric materials, may have ZT values that do
not exceed one (1). Newly developed thermoelectric materials with
low dimensional structures have demonstrated a higher figure of
merit ZT that may approach 5 or more. These materials include
zero-dimensional quantum dots, one-dimensional nano wires,
two-dimensional quantum well and superlattice thermoelectric
structures.
[0025] While bulk thermoelectric materials may be used in
thermoelectric generator 210, in certain embodiments, high ZT
thermoelectric materials may also be used. High efficiency
thermoelectric materials that may have ZT values between 1.0 and 10
may be provided consistent with the disclosed embodiments. The
described ZT values are exemplary only and not intended to be
limiting. High efficiency thermoelectric materials with other ZT
values may also be used.
[0026] In one embodiment, as shown in FIG. 3C, thermoelectric
couple 302 may include a P element 316 and an N element 318 that
may be made of zero-dimensional quantum dots of
lead-tin-selenium-telluride or other thermoelectric materials. In
another embodiment, as shown in FIG. 3D, thermoelectric couple 302
may include a P element 320 and an N element 322 that may be made
of one-dimensional nano wires of bismuth-antimony or other
thermoelectric materials. In another embodiment, as shown in FIG.
3E, thermoelectric couple 302 may include a P element 324 and an N
element 326 that may be made of two-dimensional quantum well or
superlattice thermoelectric structures of silicon-germanium,
boron-carbon or other thermoelectric materials.
[0027] As explained above, thermoelectric couple 302 may include
thermoelectric materials having low dimensional structures, such as
two-dimensional quantum wells, for example, illustrated as a series
of parallel lines in FIGS. 3E-3F. Arrangement of the low
dimensional structures relative to the flow of heat may be in-plane
(i.e., the dimension is in a same direction of the flow of heat
between junctions), as shown in FIG. 3E. Alternatively, the
arrangement of the low dimensional structures relative to the flow
of heat may also be cross-plane (i.e., the dimension is in a cross
direction of the flow of heat between junctions), as shown in FIG.
3F.
[0028] It is understood that the disclosed structures of
thermoelectric couple 302, the thermoelectric materials used, and
the ZT values of the thermoelectric materials used are exemplary
and not intended to be limiting.
[0029] Other structures and thermoelectric materials may be
included without departing from the principle and scope of
disclosed embodiments. For example, in certain embodiments,
thermoelectric couple 302 used by thermoelectric module 202 may
include P elements with different structures from N elements. For
instance, the P elements may be made of zero-dimensional quantum
dots, while the N elements may be made of two-dimensional quantum
well or superlattice thermoelectric structures.
[0030] Returning to FIG. 2, heat donative fluid flow 208 and heat
receptive fluid flow 210 may be provided to generate and/or
maintain a temperature gradient across the thermoelectric materials
with thermoelectric heat exchange system 110. Heat donative fluid
flow 208 and heat receptive fluid flow 210 may be formed
differently depending on particular applications of thermoelectric
heat exchange system 110. For example, if thermoelectric heat
exchange system 110 is used to convert waste heat of work machine
100 to electrical energy, heat donative fluid flow 208 may be
formed by accepting an exhaust stream generated by an engine of
work machine 100 (not shown). Heat receptive fluid flow 210 may be
formed by coupling a cooling line of work machine 100 with
thermoelectric module 202 to cool the thermoelectric materials
within thermoelectric module 202.
[0031] In one embodiment, thermoelectric module 202 may be coupled
with heat donative fluid flow 208 to receive a source of heat
(e.g., an exhaust stream from engine 102) on one side of
thermoelectric materials included in thermoelectric module 202.
Another side of the thermoelectric materials may be cooled by heat
receptive flow 210 (e.g., coolant in a cooling line). It should be
noted that the disclosed methods and systems may use any type of
heat exchange fluid including, for example, air, other types of
gases, liquids, or a combination of gas and liquid. Through
application of heat donative fluid flow 208 and heat receptive
fluid flow 210 to different sides of the thermoelectric materials
of thermoelectric module 202, a temperature gradient can be
generated and maintained across the thermoelectric materials. As a
result, a voltage may be generated on an output/input voltage
terminal 214 of thermoelectric module 202. Output/input voltage
terminal 214 of thermoelectric module 202 may be further coupled
with an input/output voltage terminal 216 of DC-DC converter 204.
The generated voltage may then be converted to an output voltage on
an output/input voltage terminal 218 at a desired level (e.g.,
14.4V, 30V, 300V, etc.) by DC-DC converter 204. The output voltage
on output/input voltage terminal 218 of DC-DC converter 212 may
then be sent to electric bus 212 to be used by other systems (not
shown) of work machine 100.
[0032] DC-DC converter 204 may be any type of electronic device
that accepts a DC input voltage and produces a DC output voltage at
a same or different level than the input voltage. DC-DC converter
204 may also regulate the input voltage or isolate noises on the
input. Further, DC-DC converter 204 may operate automatically based
on a default setting or operate under the control of controller 206
to perform more complex operations. Electric bus 212 may be a low
voltage bus or a high voltage bus to provide electricity for other
systems (not shown) within work machine 100. Electric bus 212 may
operate at any desired voltage level.
[0033] Controller 206 may control both thermoelectric module 202
and DC-DC converter 204 to coordinate the operations of
thermoelectric heat exchange system 110. Because the voltage
generated by thermoelectric module 202 may be dependent on the
temperature gradient across the thermoelectric material included in
thermoelectric module 202, and the temperature gradient can vary
significantly, the generated voltage may also vary significantly.
Controller 206 may control DC-DC converter 204 to account for
voltage changes on the voltage output of thermoelectric module 202
and to maintain the output voltage to electric bus 212 at a
substantially constant level.
[0034] Thermoelectric module 202 may be configured to provide high
heat exchanging efficiency. For example, thermoelectric module 202
may include a structure with a high surface area-to-volume ratio
and/or high heat transfer surface area density. As shown in FIG. 4,
thermoelectric module 202 may include a plurality of thermoelectric
heat exchange elements 402 and 410. Thermoelectric heat exchange
element 402 may include a substrate 404 and a thermoelectric
material layer 408 on substrate 404. Similarly, thermoelectric heat
exchange element 410 may also include substrate 404 and a
thermoelectric material layer 414 on substrate 404. A fluid flow
passage 406 and a fluid flow passage 412 may be created by opposing
structures (e.g., undulatory pleats) of heat exchange element 402
and heat exchange element 410. The surface-to-volume ratio and/or
heat transfer surface area density of thermoelectric module 202 may
be increased by increasing the number of fluid flow passages 406,
412 included in thermoelectric module 202.
[0035] As noted, fluid flow passages 406 and 412 may include
geometrically shaped passageways formed by opposing structures of
heat exchange element 402 and heat exchange element 410. For
example, a plurality of substrates 404, including the substrates of
elements 402 and 410, among others, may include these opposing
structures. For example, a plurality of fluid flow passages 406,
412 may be formed by pressing two substrates 404 together such that
the undulatory pleats (or another appropriate type of structure) of
one substrate oppose the undulatory pleats (or other appropriate
type of structure) of another substrate. This type of arrangement
can provide a plurality of parallel-extending and closely spaced
fluid flow passages 406 and 412. In the exemplary embodiment shown
in FIG. 4, the closely packed arrangement of fluid flow passages
406 (e.g., heat donative fluid carriers) and fluid flow passages
412 (e.g., heat receptive fluid flow carriers) may promote
efficient generation of temperature gradients across thermoelectric
material layers 408, 414.
[0036] Substrate 404 may be made from any type of heat conducting
material including any type of metal, such as steel, cooper,
aluminum, etc. In certain embodiments, substrate 404 may include
various types of ceramic materials. In one embodiment, substrate
404 may include a ductile stainless steel sheet. Substrate 404 may
be configured to provide a series of curvilinear fluid flow
passages, such as fluid flow passages 406 and 412, formed by
undulatory pleats, as described above. Packing of these fluid flow
passages, as shown in FIG. 4, can increase the heat transfer
surface area density of thermoelectric module 202. This quantity
represents a ratio between the total heat transfer surface area of
a heat transfer device and a total volume of the heat transfer
device. In certain embodiments, the heat transfer surface area
density of thermoelectric module 202 may be at least 500
Ft.sup.2/Ft.sup.3. In certain other embodiments, the heat transfer
surface area density may range between 800 Ft.sup.2/Ft.sup.3 and
1,000 Ft.sup.2/Ft.sup.3, or even higher.
[0037] Thermoelectric material layers 408 and 414 may be made from
the high efficiency thermoelectric materials described above.
Thermoelectric material layers 408 and 414 may be mounted on
substrate 404 in any suitable way. In certain embodiments,
thermoelectric material layers 408 and 414 may be formed by
depositing one or more layers of thin films of high efficiency
thermoelectric materials on substrate 404. The total thickness of
thermoelectric material layers 408 and 414 may vary. For example,
the thickness of thermoelectric material layers 408 and 414 may be
less than 100 micrometers. In one embodiment, the thickness of
thermoelectric material layers 408 and 414 may be 0.5 micrometers
or less. Further, thermoelectric material layer 408 may have a
different thickness from thermoelectric material layer 414. In
certain embodiments, thermoelectric material layer 414 may be
absent.
[0038] FIG. 5 illustrates an exemplary cross section view (i.e.,
taken through a sidewall portion of an undulatory pleat, as shown
in FIG. 4) of details of an individual thermoelectric heat exchange
element 402. As shown in FIG. 5, thermoelectric heat exchange
element 402 may include substrate 404, thermoelectric material
layer 408, and a voltage input/output 502. As explained above,
thermoelectric heat exchange element 402 may also be coupled with
fluid flow passages 406, 412. In operation of one exemplary
embodiment, an exhaust stream carrying waste heat generated by
engine 102 of work machine 100 may be introduced as heat donative
fluid flow 208 in fluid flow passage 406. Concurrently, a cooling
line may be used to provide a coolant flow that may be used as heat
receptive fluid flow 210 in fluid flow passage 412. Because
thermoelectric material layer 408 is deposited on substrate 404,
which may form a wall between fluid flow passages 408 and 412, a
temperature gradient may be generated and maintained across
thermoelectric material layer 408. The maintained temperature
gradient on thermoelectric material layer 408 may generate a
voltage on voltage input/output 502. The voltage may then be
converted into different levels by DC-DC converter 204 under the
control of controller 206 to provide electrical energy for work
machine 100. Thus, at least part of the thermal energy of the waste
heat contained in the exhaust stream may be converted to electrical
energy.
Industrial Applicability
[0039] The disclosed thermoelectric heat exchange elements may be
included in any system where there is a need for heat-to-electric
energy conversion and/or efficient heating/cooling of one or more
components. The disclosed thermoelectric heat exchange elements may
include heat exchange structures with a high heat transfer surface
area density value, or surface-to-volume ratio to provide a high
heat exchange efficiency. Further, the disclosed thermoelectric
heat exchange systems may include high efficiency thermoelectric
materials such as low dimensional thermoelectric materials. The low
dimensional thermoelectric materials may be deposited on the heat
exchange structures in one or more layers of thin films. In certain
embodiments, these high-efficiency, thin film thermoelectric
materials can be used in heat exchange structures with high surface
area to volume ratios where the use of bulk thermoelectric
materials would not be possible or practical. Further,
thermoelectric heat exchange systems including the high-efficiency,
thin film thermoelectric materials may be more efficient and better
performing than those systems including bulk thermoelectric
materials.
[0040] The disclosed thermoelectric heat exchange systems may be
incorporated in any vehicles or work machines to convert waste heat
energy into electrical power. The waste energy may be from exhaust
streams expelled by engines of the vehicles and work machines. The
disclosed methods and systems may also be used in conjunction with
heating and air conditioning systems to provide heated and/or
cooled air to the vehicles or work machines.
[0041] Other embodiments, features, aspects, and principles of the
disclosed exemplary systems will be apparent to those skilled in
the art and may be implemented in various environments not limited
to work site environments. Those skilled in the art will recognize
that the disclosed embodiments are exemplary only, other materials
and configuration may be used without departing from the scopes and
principle of the disclosed embodiments.
* * * * *